Systems and methods for thermally conditioning a wafer in a charged particle beam apparatus

ABSTRACT

An improved particle beam inspection apparatus, and more particularly, a particle beam inspection apparatus including a thermal conditioning station for preconditioning a temperature of a wafer is disclosed. The charged particle beam apparatus may scan the wafer to measure one or more characteristics of the structures on the wafer and analyze the one or more characteristics. The charged particle beam apparatus may further determine a temperature characteristic of the wafer based on the analysis of the one or more characteristics of the structure and adjust the thermal conditioning station based on the temperature characteristic.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority of U.S. application 62/756,483 whichwas filed on Nov. 6, 2018, and which is incorporated herein by referencein its entirety.

FIELD

The embodiments provided herein disclose a charged particle beaminspection apparatus, and more particularly, a particle beam inspectionapparatus including a thermal conditioning station for preconditioning atemperature of a wafer.

BACKGROUND

When manufacturing semiconductor integrated circuit (IC) chips, patterndefects or uninvited particles (residuals) inevitably appear on a waferor a mask during fabrication processes, thereby reducing the yield. Forexample, uninvited particles may be troublesome for patterns withsmaller critical feature dimensions, which have been adopted to meet theincreasingly more advanced performance requirements of IC chips.

Pattern inspection tools with a charged particle beam have been used todetect the defects or uninvited particles. These tools typically employa scanning electron microscope (SEM). In a SEM, a beam of primaryelectrons having a relatively high energy is decelerated to land on asample at a relatively low landing energy and is focused to form a probespot thereon. Due to this focused probe spot of primary electrons,secondary electrons will be generated from the surface. The secondaryelectrons may comprise backscattered electrons, secondary electrons, orAuger electrons, resulting from the interactions of the primaryelectrons with the sample. By scanning the probe spot over the samplesurface and collecting the secondary electrons, pattern inspection toolsmay obtain an image of the sample surface.

During operation of an inspection tool, the wafer is typically held by awafer stage. The inspection tool may comprise a wafer positioning devicefor positioning the wafer stage and wafer relative to the e-beam. Thismay be used to position a target area on the wafer, e.g., an area to beinspected, in an operating range of the e-beam.

SUMMARY

The embodiments provided herein disclose a charged particle beaminspection apparatus, and more particularly, a particle beam inspectionapparatus including a thermal conditioning station for preconditioning atemperature of a wafer.

In some embodiments, a method for determining a temperaturecharacteristic of a wafer using a charged particle beam apparatus isprovided. The wafer may include a plurality of structures. The methodmay include scanning the wafer with the charged particle beam apparatusto measure one or more characteristics of the plurality of structures onthe wafer. The method may also include analyzing the one or morecharacteristics of the plurality of structures. The method may furtherinclude determining the temperature characteristic based on the analysisof the one or more characteristics of the plurality of structures.

In some embodiments, a method for adjusting a charged particle beamapparatus with a thermal conditioning station is provided. The methodmay include scanning a wafer on a wafer stage with the charged particlebeam apparatus to measure one or more characteristics of a plurality ofstructures on the wafer and analyzing the one or more characteristics ofthe plurality of structures. The method may also include determining atemperature characteristic of the wafer based on the analysis of the oneor more characteristics of the plurality of structures. The method mayfurther include adjusting the thermal conditioning station based on thetemperature characteristic.

In some embodiments, a charged particle beam apparatus may include athermal conditioning station configured to precondition a wafertemperature and a particle beam imaging tool to generate one or moreimages of a wafer on a wafer stage. The charged particle beam apparatusmay further include a controller having circuitry to cause the chargedparticle beam apparatus to perform various steps. The steps may includescanning the wafer with the particle beam imaging tool to measure one ormore characteristics of a plurality of structures on the wafer andanalyzing the one or more characteristics of the plurality ofstructures. The steps may also include determining a temperaturecharacteristic of the wafer based on the analysis of the one or morecharacteristics of the plurality of structures and adjusting the thermalconditioning station based on the temperature characteristic.

Other advantages of the present invention will become apparent from thefollowing description taken in conjunction with the accompanyingdrawings wherein are set forth, by way of illustration and example,certain embodiments of the present invention.

BRIEF DESCRIPTION OF FIGURES

The above and other aspects of the present disclosure will become moreapparent from the description of exemplary embodiments, taken inconjunction with the accompanying drawings.

FIG. 1A is a schematic diagram illustrating an exemplary waferdeformation effect in a charged particle beam inspection system.

FIG. 1B a schematic diagram illustrating an exemplary charged particlebeam inspection system, consistent with embodiments of the presentdisclosure.

FIG. 1C is a schematic diagram illustrating an exemplary wafer loadingsequence in the charged particle beam inspection system of FIG. 1B,consistent with embodiments of the present disclosure.

FIG. 2 is a schematic diagram illustrating an exemplary electron beamtool, consistent with embodiments of the present disclosure.

FIG. 3 is an exemplary graph showing a wafer temperature change overtime in a charged particle beam inspection system.

FIG. 4 is a schematic diagram of an exemplary charged particle beaminspection system with a thermal conditioning station, consistent withembodiments of the present disclosure.

FIGS. 5 and 6 is an exemplary graph showing a wafer temperature changeover time in relation to a temperature setpoint of the thermalconditioning process, consistent with embodiments of the presentdisclosure.

FIGS. 7 and 8 is a schematic diagram illustrating exemplary images of awafer with a plurality of structures, consistent with embodiments of thepresent disclosure.

FIG. 9 is a flow chart illustrating an exemplary method for conditioninga wafer temperature, consistent with embodiments of the presentdisclosure.

DETAILED DESCRIPTION

Reference will now be made in detail to exemplary embodiments, examplesof which are illustrated in the accompanying drawings. The followingdescription refers to the accompanying drawings in which the samenumbers in different drawings represent the same or similar elementsunless otherwise represented. The implementations set forth in thefollowing description of exemplary embodiments do not represent allimplementations consistent with the invention. Instead, they are merelyexamples of apparatuses and methods consistent with aspects related tothe invention as recited in the appended claims.

The enhanced computing power of electronic devices, while reducing thephysical size of the devices, can be accomplished by significantlyincreasing the packing density of circuit components such astransistors, capacitors, diodes, etc. on an IC chip. For example, an ICchip of a smart phone, which is the size of a thumbnail, may includeover 2 billion transistors, the size of each transistor being less than1/1000th of a human hair. Thus, it is not surprising that semiconductorIC manufacturing is a complex and time-consuming process, with hundredsof individual steps. Errors in even one step have the potential todramatically affect the functioning of the final product. Even one“killer defect” can cause device failure. The goal of the manufacturingprocess is to improve the overall yield of the process. For example, fora 50-step process to get to a 75% yield, each individual step must havea yield greater than 99.4%, and if the individual step yield is 95%, theoverall process yield drops to 7%.

While high process yield is desirable in an IC chip manufacturingfacility, maintaining a high wafer throughput, defined as the number ofwafers processed per hour, is also essential. High process yield andhigh wafer throughput can be impacted by the presence of defects,especially if operator intervention is required for reviewing thedefects. Thus, high throughput detection and identification of micro andnano-sized defects by inspection tools (such as a SEM) is essential formaintaining high yield and low cost.

A SEM scans the surface of a wafer with a focused beam of electrons. Theelectrons interact with the wafer and generate secondary electrons. Byscanning the wafer with an electron beam and capturing the secondaryelectrons with a detector, a SEM creates an image of the wafer thatshows the internal device structure in the area of the wafer beinginspected.

One of the problems with a conventional inspection system is that awafer being scanned may change its shape or size while the scanning isin progress. For example, when the wafer is placed on an inspectionplatform, the temperature of wafer can be different from the temperatureof the platform. This temperature difference may cause a wafertemperature drift (e.g., the temperature of the wafer gradually andcontinuously changes towards a stable point, which is usually close tothe temperature of the inspection system), thereby resulting in thechange in the shape or size of the wafer. If the wafer temperatureincreases, the wafer would expand; if the wafer temperature decreases,the wafer would shrink. This change in the shape or size of the wafercan cause inaccurate inspection results.

Therefore, an operator, who is inspecting a wafer using a conventionalparticle beam inspection system, needs to wait for the wafer to becometemperature-stabilized before starting the inspection. This temperaturestabilization is required because the wafer changes size as thetemperature changes, which causes elements on the wafer to move as thewafer expands or contracts. For example, FIG. 1A shows that elements180, 182, 184, and 186 can move to new locations 170, 172, 174, and 178as a wafer 160 expands due to the temperature change. And when theprecision for inspecting a wafer is in nanometers, this change inlocation is material. Accordingly, for the operator to precisely locateand inspect the elements on the wafer, the operator must wait until thewafer temperature stabilizes. Therefore, for high throughput inspection,some of the newer inspection systems perform a thermal conditioning of awafer before placing the wafer on the inspection platform. By making thewafer temperature close to the temperature of the wafer stage beforeplacing the wafer onto the wafer stage, the inspection can begin withmuch less delay. Therefore, the operator can inspect more wafers withina given period of time, thereby achieving an increased throughput.

If the inspection system can use the actual temperature of the wafer,the thermal conditioning process can be further optimized. However,measuring the actual wafer temperature is difficult.

Placing a thermometer on the wafer can contaminate the inspectionenvironment with unwanted particles (e.g., dust), which can degrade theaccuracy of wafer inspection. Contactless thermometers, like Infrared(IR) temperature sensors, may avoid the contamination problem, but theaccuracy of IR sensors is still too low for this purpose.

One aspect of the present disclosure includes systems and methods thatcan measure the temperature characteristics of the wafer indirectly andwith adequate accuracy without using any component, such as athermometer, that can contaminate the inspection environment. Asdescribed earlier with respect to FIG. 1A, the wafer can change the size(e.g., expand or shrink) when the wafer temperature is changing.Therefore, the wafer size change is closely related to the wafertemperature change. By obtaining multiple images of the wafer andcomparing the locations of some of structures on the wafer, thetemperature characteristics of the wafer can be determined with therequired accuracy, and without causing any contamination.

Relative dimensions of components in drawings may be exaggerated forclarity. Within the following description of drawings the same or likereference numbers refer to the same or like components or entities, andonly the differences with respect to the individual embodiments aredescribed. As used herein, unless specifically stated otherwise, theterm “or” encompasses all possible combinations, except whereinfeasible. For example, if it is stated that a database can include Aor B, then, unless specifically stated otherwise or infeasible, thedatabase can include A, or B, or A and B. As a second example, if it isstated that a database can include A, B, or C, then, unless specificallystated otherwise or infeasible, the database can include A, or B, or C,or A and B, or A and C, or B and C, or A and B and C.

Reference is now made to FIG. 1B, which is a schematic diagramillustrating an exemplary charged particle beam inspection system 100,consistent with embodiments of the present disclosure. As shown in FIG.1B, charged particle beam inspection system 100 may include a mainchamber 10, a load lock chamber 20, an electron beam tool 40, and anequipment front end module (EFEM) 30. Electron beam tool 40 may belocated within main chamber 10. While the description and drawings aredirected to an electron beam, it is appreciated that the embodiments arenot used to limit the present invention to specific charged particles.It is further appreciated that electron beam tool 40 can be asingle-beam tool utilizing a single electron beam or a multi-beam toolutilizing multiple electron beams.

EFEM 30 may include a first loading port 30 a and a second loading port30 b. EFEM 30 may include additional loading port(s). First loading port30 a and second loading port 30 b may, for example, receive wafer frontopening unified pods (FOUPs) that contain wafers (e.g., semiconductorwafers or wafers made of other material(s)) or samples to be inspected(wafers and samples are collectively referred to as “wafers” hereafter).One or more robot arms (e.g., robot arm 11 shown in FIG. 1C) in EFEM 30transport the wafers to load lock chamber 20.

Load lock chamber 20 may be connected to a load lock vacuum pump system(not shown), which removes gas molecules in load lock chamber 20 toreach a first pressure below the atmospheric pressure. After reachingthe first pressure, one or more robot arms (e.g., robot arm 12 shown inFIG. 1C) transport the wafer from load lock chamber 20 to main chamber10. Main chamber 10 is connected to a main chamber vacuum pump system(not shown), which removes gas molecules in main chamber 10 to reach asecond pressure below the first pressure. After reaching the secondpressure, the wafer is subject to inspection by electron beam tool 40.

A controller 50 may be electronically connected to electron beam tool 40or any other parts of charged particle beam inspection system 100.Controller 50 may be a computer configured to execute various controlsof charged particle beam inspection system 100. Controller 50 may alsoinclude a processing circuitry configured to execute various signal andimage processing functions. While controller 50 is shown in FIG. 1B asbeing outside of the structure that includes main chamber 10, load lockchamber 20, and EFEM 30, it is appreciated that controller 50 may bepart of the structure. While the present disclosure provides examples ofmain chamber 10 housing an electron beam inspection tool, it should benoted that aspects of the disclosure in their broadest sense are notlimited to a chamber housing an electron beam inspection tool. Rather,it is appreciated that the foregoing principles may also be applied toother tools that operate under the second pressure.

Reference is now made to FIG. 1C, which is a schematic diagramillustrating an exemplary wafer loading sequence in charged particlebeam inspection system 100 of FIG. 1B, consistent with embodiments ofthe present disclosure. In some embodiments, charged particle beaminspection system 100 may include a robot arm 11 located in EFEM 30 anda robot arm 12 located in main chamber 10. In some embodiments, EFEM 30may also include a pre-aligner 60 configured to position a waferaccurately before transporting the wafer to load lock chamber 20.

In some embodiments, first loading port 30 a and second loading port 30b, for example, may receive wafer front opening unified pods (FOUPs)that contain wafers. Robot arm 11 in EFEM 30 may transport the wafersfrom any of the loading ports to pre-aligner 60 for assisting with thepositioning. Pre-aligner 60 may use mechanical or optical aligningmethods to position the wafers.

After pre-alignment, robot arm 11 may transport the wafers to load lockchamber 20.

After the wafers are transported to load lock chamber 20, a load lockvacuum pump (not shown) may remove gas molecules in load lock chamber 20to reach a first pressure below the atmospheric pressure. After reachingthe first pressure, a robot arm 12 may transport the wafer from loadlock chamber 20 to a wafer stage 80 of electron beam tool 40 in mainchamber 10. Main chamber 10 is connected to a main chamber vacuum pumpsystem (not shown), which removes gas molecules in main chamber 10 toreach a second pressure below the first pressure. After reaching thesecond pressure, the wafer may be subject to inspection by electron beamtool.

In some embodiments, main chamber 10 may include a parking station 70configured to temporarily store a wafer before inspection. For example,when the inspection of a first wafer is completed, the first wafer maybe unloaded from wafer stage 80, and then robot arm 12 may transport asecond wafer from parking station 70 to wafer stage 80. Afterwards,robot arm 12 may transport a third wafer from load lock chamber 20 toparking station 70 to temporarily store the third wafer until theinspection for the second wafer is finished.

In some embodiments, to improve the overall throughput of inspectionsystem, charged particle beam inspection system 100 may perform athermal conditioning of a wafer before loading the wafer onto waferstage 80. This pre-inspection thermal conditioning may occur inpre-aligner 60, load lock chamber 20, parking station 70, or any otherplace suitable for thermally conditioning the wafer before moving it towafer stage 80.

Reference is now made to FIG. 2, which is a schematic diagramillustrating an exemplary inspection system 200 that may be part of thecharged particle beam inspection system of FIGS. 1B and 1C, consistentwith embodiments of the present disclosure. Inspection system 200 mayinclude an electron beam tool 40 and a controller 50.

Electron beam tool 40 may include a motorized wafer stage 201 (similarto wafer stage 80 of FIG. 1C). Electron beam tool 40 may also include awafer holder 202 supported by motorized wafer stage 201 to hold a wafer203 to be inspected. Electron beam tool 40 may further include acompound objective lens 204, electron detector 206 (which includeselectron sensor surfaces), an objective aperture 208, a condenser lens210, a beam limit aperture 212, a gun aperture 214, an anode 216, and acathode 218, one or more of which may be aligned with an optical axis217 of electron beam tool 40. In some embodiments, detector 206 may bearranged off axis 217.

Compound objective lens 204, in some embodiments, may include a modifiedswing objective retarding immersion lens (SORIL), which may include apole piece 204 a, a control electrode 204 b, a deflector or a set ofdeflectors 204 c, and an exciting coil 204 d. In some embodiments,electron beam tool 40 may additionally include an energy dispersiveX-ray spectrometer (EDS) detector (not shown) to characterize thematerials on the wafer.

A primary electron beam 220 may be emitted from cathode 218 by applyinga voltage between anode 216 and cathode 218. Primary electron beam 220may pass through gun aperture 214 and beam limit aperture 212, both ofwhich may determine the current of electron beam entering condenser lens210, which resides below beam limit aperture 212. Condenser lens 210 mayfocus primary electron beam 220 before the beam enters objectiveaperture 208 to set the current of the electron beam before enteringcompound objective lens 204.

Compound objective lens 204 may focus primary electron beam 220 ontowafer 203 for inspection and can form a probe spot 222 on surface ofwafer 203. Deflector(s) 204 c may deflect primary electron beam 220 toscan probe spot 222 over wafer 203. For example, in a scanning process,deflector(s) 204 c may be controlled to deflect primary electron beam220 sequentially onto different locations of top surface of wafer 203 atdifferent time points, to provide data for image reconstruction fordifferent parts of wafer 203. Moreover, in some embodiments, deflector204 c may also be controlled to deflect primary electron beam 220 ontodifferent sides of wafer 203 at a particular location, at different timepoints, to provide data for stereo image reconstruction of the waferstructure at that location. Further, in some embodiments, anode 216 andcathode 218 may be configured to generate multiple primary electronbeams 220, and electron beam tool 40 may include a plurality ofdeflectors 204 c to project the multiple primary electron beams 220 todifferent parts/sides of wafer 203 at the same time.

When a current is applied onto exciting coil 204 d, an axially-symmetric(i.e., symmetric around optical axis 217) magnetic field may begenerated in the wafer surface area. A part of wafer 203 being scannedby primary electron beam 220 may be immersed in the magnetic field. Insome embodiments, different voltages may be applied onto wafer 203, polepiece 204 a, and control electrode 204 b, to generate an axial symmetricretarding electric field near the wafer surface. The electric field mayreduce the energy of impinging primary electron beam 220 near thesurface of the wafer before electrons of the beam collide with wafer203. Control electrode 204 b, being electrically isolated from polepiece 204 a, may control an axially-symmetric electric field on thewafer to prevent micro-arcing of the wafer and to ensure proper beamfocus at the wafer surface with the axially-symmetric magnetic fieldtogether.

A secondary electron beam 230 may be emitted from the part of wafer 203upon receiving primary electron beam 220. Secondary electron beam 230may comprise backscattered electrons, secondary electrons, or Augerelectrons, resulting from the interactions of the primary electrons withwafer 203. Secondary electron beam 230 may be received by sensorsurfaces of electron detector 206. In some embodiments, electrondetector 206 may generate a signal (e.g., a voltage, a current, etc.)that represents an intensity of secondary electron beam 230 and mayprovide the signal to controller 50 in communication with electrondetector 206. The intensity of secondary electron beam 230 may varyaccording to the external or internal structure of wafer 203, and thusmay indicate whether wafer 203 includes defects. Moreover, as discussedabove, primary electron beam 220 may be projected onto differentlocations of the top surface of wafer 203, or different sides of wafer203 at a particular location, to generate secondary electron beams 230of different intensities. Therefore, by mapping the intensity ofsecondary electron beam 230 with the areas of wafer 203, imageprocessing circuitry in controller 50 may reconstruct an image thatreflects the characteristics of internal or external structures of wafer203.

In some embodiments, controller 50 may comprise image processing systemthat includes an image acquirer (not shown) and a storage (not shown).The image acquirer may comprise one or more processors. For example, theimage acquirer may comprise a computer, server, mainframe host,terminals, personal computer, any kind of mobile computing devices, andthe like, or a combination thereof. The image acquirer may becommunicatively coupled to electron detector 206 of electron beam tool40 through a medium such as an electrical conductor, optical fibercable, portable storage media, IR, Bluetooth, internet, wirelessnetwork, wireless radio, among others, or a combination thereof. In someembodiments, the image acquirer may receive a signal from electrondetector 206 and may construct an image. The image acquirer may thusacquire images of wafer 203. The image acquirer may also perform variouspost-processing functions, such as generating contours, superimposingindicators on an acquired image, and the like. The image acquirer may beconfigured to perform adjustments of brightness and contrast, etc. ofacquired images. In some embodiments, the storage may be a storagemedium such as a hard disk, flash drive, cloud storage, random accessmemory (RAM), other types of computer readable memory, and the like. Thestorage may be coupled with the image acquirer and may be used forsaving scanned raw image data as original images, and post-processedimages.

In some embodiments, the image acquirer may acquire one or more imagesof wafer 203 based on an imaging signal received from detector 206. Animaging signal may correspond to a scanning operation for conductingcharged particle imaging. An acquired image may be a single imagecomprising a plurality of imaging areas. The single image may be storedin the storage. The single image may be an original image that may bedivided into a plurality of regions. Each of the regions may compriseone imaging area containing a feature of wafer 203. The acquired imagesmay comprise multiple images of a single imaging area of wafer 203sampled multiple times over a time sequence. The multiple images may bestored in storage 270. In some embodiments, controller 50 may beconfigured to perform image processing steps with the multiple images ofthe same location of wafer 203.

In some embodiments, controller 50 may include measurement circuitries(e.g., analog-to-digital converters) to obtain a distribution of thedetected secondary electrons. The electron distribution data collectedduring a detection time window, in combination with corresponding scanpath data of primary electron beam 220 incident on the wafer surface,can be used to reconstruct images of the wafer structures underinspection. The reconstructed images can be used to reveal variousfeatures of the internal or external structures of wafer 203, andthereby can be used to reveal any defects that may exist in the wafer.

In some embodiments, controller 50 may perform a wafer alignmentprocess. The alignment process may include analyzing one or more imagesof wafer 203 with respect to a reference image. The wafer image may showone or more structures or patterns on the wafer, wherein the structuresor the patterns are embedded on the wafer during a semiconductormanufacturing process. Controller 50 may analyze the wafer image andcompare the locations of the one or more structures to the locations ofthe structures in the reference image. Controller 50 may adjust systemconfiguration to compensate the amount of misalignment.

Moreover, although FIG. 2 shows that electron beam tool 40 uses a singleprimary electron beam, it is appreciated that electron beam tool 40 mayalso be a multi-beam inspection tool that uses multiple primary electronbeams. The present disclosure does not limit the number of primaryelectron beams used in electron beam tool 40.

Reference is now made to FIG. 3, which is an exemplary graph showing awafer temperature change over time for a charged particle beaminspection system. The vertical axis represents temperature change, andthe horizontal axis represents passage of time. The graph shows that thewafer temperature changes over time while the wafer is processed throughmultiple stages of wafer load sequence. At time 330, the wafer is loadedto a load lock chamber. At time 340, the wafer is transported and loadedto wafer stage. At time 345, a wafer inspection begins. At time 350, thewafer inspection ends, and the wafer is unloaded from the wafer stage.During period 320, the wafer stays on the wafer stage.

According to the exemplary data shown in FIG. 3, when a wafer is loadedto the load lock chamber at time 330, the temperature of the wafer isapproximately 22 degrees (annotated as 312). After the wafer istransported to a load lock chamber, the wafer temperature sharply dropsfrom temperature 312 to temperature 314. Exemplary data show that thistemperature drop, which occurs when the load lock chamber is pumped downto a vacuum, may be approximately one to two degrees. This suddentemperature drop is referred to as a pump-down effect.

Subsequently, when the wafer is transported and loaded onto the waferstage (e.g., wafer stage 80 of FIG. 1C) at time 340, the wafertemperature (annotated 314) and the wafer stage temperature (not shown,but close to an equilibrium temperature 310) may be at differenttemperatures. Exemplary data show that this difference may beapproximately up to three degrees.

This temperature difference between the wafer and the wafer stage causeswafer temperature drift towards the wafer stage temperature. Forexample, the graph in FIG. 3 shows that the wafer temperature changesduring period 320. Under such circumstances, heat transfer occursbetween the wafer and the wafer stage, thereby resulting in adeformation (e.g., a thermal expansion shown in FIG. 1A) of the wafer(or the wafer stage). While the wafer stage or wafer is undergoing athermal deformation, the inspection of the target area may not bepossible or may have a reduced accuracy. Thus, to perform a moreaccurate inspection, the system waits for a significant period of time(waiting period 325) until the wafer temperature stabilizes at anequilibrium temperature 310 before an inspection can commence at time345. Therefore, reducing waiting period 325 may improve the throughputof the inspection system. In some embodiments, the wafer may bethermally preconditioned to reduce temperature difference 360, therebyresulting in shorter waiting period 325.

An example of wafer stage for quicker temperature stabilization may befound in European Patent Application No. EPI 8174642.1, titled PARTICLEBEAM APPARATUS and filed on May 28, 2018, which is incorporated byreference in its entirety. Another way to cope with this longstabilization time is conditioning the wafer temperature by pre-heatingor pre-cooling the wafer to match the temperature of the wafer stagebefore the wafer is loaded onto the wafer stage. Examples of suchembodiments may be found in U.S. Patent Application No. 62/699,643,titled PARTICLE BEAM INSPECTION APPARATUS and filed on Jul. 17, 2018,which is incorporated by reference in its entirety.

Reference is now made to FIG. 4, which shows an exemplary chargedparticle beam inspection system 400 with a thermal conditioning station410, consistent with embodiments of the present disclosure. In someembodiments, inspection system 400 may include thermal conditioningstation 410, a main chamber 490, a controller 450, and a heater/cooler460. Main chamber 490 may include an electron beam tool (not shown; suchas electron beam tool 40 of FIG. 2) to obtain images of a wafer 480 (awafer currently under inspection). While inspection of wafer 480 is inprogress, thermal conditioning station 410 may perform a thermalconditioning of a wafer 420 (a wafer in line to be inspected after wafer480 inspection is completed) to change the temperature of wafer 420 inpreparation for the inspection step.

In some embodiments, thermal conditioning station 410 may include aplurality of supporting structures 425 and a conditioning plate 415configured to transfer heat to wafer 420. In other embodiments,conditioning plate 415 may be configured to additionally oralternatively transfer heat from wafer 420. Supporting structures 425,coupled to conditioning plate 415, may support wafer 420 such that thereis a space between wafer 420 and conditioning plate 415. While it isappreciated that more efficient heat transfer may be achieved as wafer420 is positioned closer to conditioning plate 415, in some embodiments,it may be desirable to have sufficient distance in between wafer 420 andconditioning plate 415 to provide space for a robot arm to lift ortransport wafer 420. In some embodiments, the distance between wafer 420and conditioning plate 415 may be in a range of 1.5 mm to 10 mm toprovide space to accommodate a variety of robot arm sizes in lifting ortransporting a wafer. In some embodiments, the distance between wafer420 and conditioning plate 415 may be in a range of 3 mm to 5 mm toprovide space to accommodate a certain type of robot arms whileproviding more efficient heat transfer, without requiring a specialtreatment for robot arm transportation. In some embodiments, a specialmechanism for lifting wafer 420 may be used, allowing the distance to benarrower.

Furthermore, even if two supporting structures 425 are shown in FIG. 3A,it is appreciated that thermal conditioning station 410 may include anynumber of supporting structures 425. In some embodiments, wafer 420 maybe passively placed on top of supporting structures 425 without anymeans of active coupling (e.g. electrostatic clamping). In otherembodiments, wafer 420 may be held onto supporting structures 425 usingan active holding mean, such as electrostatic clamping.

In some embodiments, a pre-aligner (such as pre-aligner 60 of FIG. 1C)may function as thermal conditioning station 410. In some embodiments, aparking station (such as parking station 70 of FIG. 1C) may function asthermal conditioning station 410.

In some embodiments, a load lock chamber (such as load lock chamber 20of FIG. 1C) may function as thermal conditioning station 410. In suchembodiments, the load lock chamber (i.e., thermal conditioning station410) may be configured to change the internal pressure betweenatmospheric and vacuum. A pump, such as a turbo pump (not shown), may beconnected to the load lock chamber to maintain a vacuum level at anappropriate level for conditioning the temperature of wafer 420. It isappreciated that the pump may be a type of pump different from a turbopump as long as the pump is suitable for establishing a vacuum in theload lock chamber.

In some embodiments, conditioning plate 415 may include a heat transferelement 440 configured to change the temperature of conditioning plate415, which in turn affect the temperature of wafer 420. Heat transferelement 440 may be coupled to heater/cooler 460. In some embodiments,heater/cooler 460 may be placed outside of thermal conditioning station410. In other embodiments, heater/cooler 460 may be placed inside ofthermal conditioning station 410.

Controller 450 may be configured to adjust heater/cooler 460 or heattransfer element 440, via a control signal 434, to change thetemperature of conditioning plate 415, which in turn affects thetemperature of wafer 420. In some embodiments, controller 450 mayperform various analyses based on multiple data inputs (e.g., viacommunication channels 431, 432, and 433) to adjust a temperaturesetpoint for the thermal conditioning process, thereby controllingheater/cooler 460 or heat transfer element 440 via control signal 434.

In some embodiments, controller 450 may receive a stage-temperature dataabout the temperature of wafer stage 495 in a main chamber 490. Forexample, controller 450 may receive, via communication channel 431, anelectric signal conveying the stage-temperature data from a temperaturesensor 496 configured to measure the temperature of wafer stage 495. Insuch embodiments, controller 450 may adjust the temperature setpoint ofthermal conditioning process based on the received stage-temperaturedata of wafer stage 495 and control heater/cooler 460 to adjust thetemperature of conditioning plate 415 according to the adjustedtemperature setpoint.

Controller 450 may additionally or alternatively use information fromthe electron beam tool to adjust thermal conditioning station 410. Wafer480 may have already been thermally conditioned in thermal conditioningstation 410 before being transported to wafer stage 495 for inspection.Therefore, by obtaining and processing the temperature characteristicsof the wafer 480 that has been already thermally preconditioned,controller 450 may determine the effectiveness of thermal conditioningprocess and reconfigure thermal conditioning station 410 to treat thewafers in pipeline (e.g., wafer 420 and other wafers in FOUPs) moreefficiently, thereby improving the overall throughput of chargedparticle beam inspection system 400. For example, controller 450 mayadjust the temperature setpoint of the thermal conditioning processbased on the temperature characteristic of wafer 480.

To determine the temperature characteristic of wafer 480, controller 450may receive, via communication channel 433, some measuredcharacteristics of wafer 480. These characteristics of wafer 480 mayinclude locations of a structures on the wafer or distances between thestructures.

The temperature characteristic of wafer 480, in some embodiments, may beinformation about temperature of wafer 480. The temperature informationof wafer 480 may be obtained by direct measurement (e.g., using acontact- or contactless-temperature sensor) or indirect measurement(e.g., analyzing physical properties of wafer 480). One of the ways toindirectly measure the temperature information of wafer 480 is using analignment data of wafer 480. For example, in some embodiments,controller 450 may receive one or more images of wafer 480 (such aswafer images 710 and 760 of FIG. 7 or wafer images 810, 820, and 830 ofFIG. 8) via communication channel 433. The one or more images may beimages of one or more portions of wafer 480. In other embodiments,controller 450 may receive scanning data from the electron beam tool inmain chamber 490 and construct multiple wafer images or multiple imagesof portions of the wafer. Controller 450 may then analyze the images ofwafer 480 to identify a temperature characteristic of wafer 480. Thisindirect measurement process is described in further detail with respectto FIGS. 7 and 8 in the following sections.

In some embodiments, controller 450 may receive a heater-temperaturedata about the temperature of output of heater/cooler 460 viacommunication channel 432. In such embodiments, controller 450 maydynamically adjust heater/cooler 460 with control signal 434 based onthe feedback information (the received heater-temperature data) tocontrol the temperature of conditioning plate 415. For example, in someembodiments, heater/cooler 460 may be a water heater or water cooler. Insuch embodiments, heated or cooled water flows through heat transferelements 440 in conditioning plate 415, and controller 450 may receivethe heater-temperature data about the temperature of water at the outputof heater/cooler 460. Controller 450 may adjust heater/cooler 460 basedon the water temperature. Controller 450 may receive an electric signalconveying the heater-temperature data from a temperature sensor 465configured to measure the temperature of water, via communicationchannel 432. In some embodiments, controller 450 may use the receivedheater-temperature data to adjust the temperature setpoint of thethermal conditioning process.

In some embodiments, communication channels 431, 432, and 433 andcontrol signal 434 may comprise a medium such as an electricalconductor, optical fiber cable, portable storage media, IR, Bluetooth,internet, wireless network, wireless radio, among others, or acombination thereof. In some embodiments, controller 450 may be furtheroptimized with additional temperature sensors. For example, in someembodiments, system may additionally include one or more sensorsconfigured to measure the temperature of wafer 420, wafer 480, orconditioning plate 415.

FIG. 5 shows an exemplary graph showing a wafer temperature change overtime in a thermal conditioning station (such as thermal conditioningstation 410 in FIG. 4), in relation to a temperature setpoint of thethermal conditioning process. The thermal conditioning process begins attime 530. As the heat is transferred to the wafer, the temperature ofwafer gradually approaches an equilibrium temperature 510. The thermalconditioning process may continue until time 540, at which thetemperature of wafer stabilizes approximately at equilibrium temperature510. The thermal conditioning station may be controlled by a controller(such as controller 450 of FIG. 4) with a temperature setpoint 520. Asshown in FIG. 5, in some embodiments, the controller may drivetemperature setpoint 520 to a constant value.

FIG. 6 shows another exemplary graph showing a wafer temperature changeover time during wafer temperature conditioning. Similar to anembodiment in FIG. 5, the thermal conditioning process begins at time630 and ends at time 640, when the temperature of wafer stabilizesapproximately at an equilibrium temperature 610. In this embodiment, thecontroller may adjust a temperature setpoint 620 dynamically inreal-time to reduce the time needed for thermal conditioning. Forexample, temperature setpoint 620 may be set high initially to quicklychange the temperature of wafer, then gradually lowered as the wafertemperature approaches towards equilibrium temperature 610.

Reference is now made to FIG. 7, which is a schematic diagramillustrating exemplary images of a wafer with a plurality of structures,consistent with embodiments of the present disclosure. In someembodiments, an alignment data of a wafer under inspection (such aswafer 480 of FIG. 4) may be used to determine a temperaturecharacteristic of the wafer (e.g., the temperature information of thewafer). For example, as described with respect to FIG. 4, a controller(such as controller 450 of FIG. 4) may receive one or more images of thewafer. The one or more images may be images of one or more portions ofthe wafer. The controller may then analyze the received images of thewafer or portions of the wafer to determine a temperature characteristicof wafer. The controller may use the temperature characteristic toadjust the temperature setpoint of the thermal conditioning station(such as thermal conditioning station 410 of FIG. 4).

As shown in FIG. 7, in some embodiments, a wafer image 710 may becompared with a reference wafer image 760 to determine the relative sizeof the wafer. Based on the relative size of the wafer, the temperaturecharacteristics of the wafer may be determined. For example, if thewafer (as shown in wafer image 710) is smaller than the reference image,the temperature of the wafer may be lower than the correspondingreference temperature. If the wafer is larger than the reference image,the temperature of the wafer may be higher than the correspondingreference temperature.

In such embodiments, a controller (such as controller 450 of FIG. 4) mayreceive wafer image 710 (or images of portions of the wafer), whichshows one or more structures or patterns on the wafer, wherein thestructures or the patterns are embedded on the wafer during asemiconductor manufacturing process. Wafer image 710 (or an image of aportion of the wafer) may be compared to the reference so that arelative location of a known structure on the wafer can be found withrespect to corresponding structures in the reference. Using similartechniques, the locations of multiple structures in the wafer and thereference may be determined, and also the distances between them basedon the SEM scans may be determined. For example, wafer image 710 showsthat four such structures at location 730, 732, 734, and 736. Thecontroller may analyze wafer image 710 and determine the locations ofthe structures on the wafer. The controller may also determine thedistances between the structures, such as distance 742 between thestructures at locations 732 and 736, and distance 744 between thestructures at locations 734 and 730.

In some embodiments, these measured characteristics of the wafer may becompared to the expected characteristics of the wafer in a referencedata. The reference data may include a GDS layout data. For example,reference wafer image 760 shows that the structures are expected to befound at locations 770, 772, 774, and 776. Accordingly, the distancesbetween the expected locations of the structures may be obtained, suchas distance 782 between the expected locations 772 and 776, and distance784 between the expected locations 774 and 770. In such embodiments, thecontroller may compare distances 742, 744 to distances 782, 784,respectively. The controller may determine a wafer scaling factor usingthe equation below based on the measured distance 742 and 744 and theexpected distance 782 and 784:

$\begin{matrix}{{{Wafer}\mspace{14mu} {Scaling}\mspace{14mu} {Factor}} = {\frac{1}{2} \times \left( {\frac{{distance}\mspace{14mu} 742}{{distance}\mspace{14mu} 782} + \frac{{distance}\mspace{14mu} 744}{{distance}\mspace{14mu} 784}} \right)}} & \left( {{Equation}\mspace{14mu} 1} \right)\end{matrix}$

While Equation 1 shows that the Wafer Scaling Factor may be determinedbased on a comparison between two measured distances to two expecteddistances, it is appreciated that the Wafer Scaling Factor may bedetermined based on a comparison between one or more measured distancesto the corresponding expected distances.

In some embodiments, a known temperature of wafer may be associated withreference wafer image 760. In such embodiments, the controller mayestimate the actual wafer temperature corresponding to wafer image 710using equation below:

$\begin{matrix}{T_{wafer} = {T_{reference} + \frac{{Wafer}\mspace{14mu} {Scaling}\mspace{14mu} {Factor}}{\alpha_{wafer}}}} & \left( {{Equation}\mspace{14mu} 2} \right)\end{matrix}$

where, α_(wafer) is the linear expansion coefficient of wafer material(for example, for Silicon, α_(Si)≅2.56·10⁻⁶·K⁻¹) and T_(reference) isthe known wafer temperature associated with wafer image 760. Someexamples of wafer material include germanium, gallium arsenide, amongothers).

The determined wafer temperature (T_(wafer)) may be provided to thecontroller to adjust the temperature setpoint of a thermal conditioningstation (such as thermal conditioning station 410 of FIG. 4).

Reference is now made to FIG. 8, which is a schematic diagramillustrating exemplary images of a wafer with a plurality of structures,consistent with embodiments of the present disclosure. In someembodiments, the wafer-level alignment steps may be performed severaltimes over a time sequence to produce multiple images of the wafer. Acontroller (such as controller 450 of FIG. 4) may analyze those multiplewafer images to obtain the temperature characteristic of the wafer.

As shown in FIG. 8, wafer images 810, 820, and 830 may be produced atdifferent times over a time sequence. As explained with respect to FIG.3, if the temperature of a wafer under inspection (such as wafer 480 ofFIG. 4) is different from the temperature of a wafer stage (such aswafer stage 495 of FIG. 4), the wafer temperature may gradually drifttowards the temperature of the wafer stage, thereby resulting in adeformation (e.g., a thermal expansion shown in FIG. 1A) of the wafer.With multiple wafer images taken over a time sequence, the controllermay identify the characteristic of the deformation (e.g., rate or speedof expansion), which may be correlated with the change of wafertemperature over time.

For example, wafer images 810, 820, and 830, obtained at time t₁, t₂,and t₃, respectively, show the movement of a plurality of structures onthe wafer. In other words, the structures move from locations 811, 812,813, 814 at time t₁, through locations 821, 822, 823, 824 at time t₂,and finally to locations 831, 832, 833, 834 at time t₃, respectively.

This temperature drift may have the following profile:

T _(wafer(t)) −T _(wafer stage)=(T _(wafer(0)) −T _(wafer stage))×e^(−t/τ)  (Equation 3)

where T_(wafer(t)) is the wafer temperature, t is time, T_(wafer(0)) isthe wafer temperature at t=0, when the wafer is loaded to the waferstage; T_(wafer stage) is the temperature of the wafer stage. τrepresent the thermal time constant:

$\begin{matrix}{\tau = \frac{C_{wafer} \times M_{wafer}}{h \times A_{wafer}}} & \left( {{Equation}\mspace{14mu} 4} \right)\end{matrix}$

where C_(wafer) is the heat capacity of silicon, M_(wafer) is the massof the wafer, h is the heat transfer coefficient between the wafer andthe wafer stage, and A_(wafer) is the effective surface area of thewafer.

With multiple measurements of the characteristics of the structures onthe wafer, the relative wafer temperatures at several time steps (e.g.,t₁, t₂, and t₃) may be determined using the Wafer Scaling Factorequation (Equation 1). Based on these relative wafer temperatures atseveral time steps, T_(wafer(0))−T_(wafer stage) (i.e., the temperaturedifference between the wafer and the wafer stage at t=0 when the waferis loaded to the wafer stage) may be determined with a fitting process.For example, the controller may perform an exponential extrapolationprocess based on Equation 3 to determine T_(wafer(0))−T_(wafer stage).

The determined T_(wafer(0))−T_(wafer stage) may be provided to thecontroller to adjust the temperature setpoint of the thermalconditioning station to minimize the wafer temperature drift.

Reference is now made to FIG. 9, which is a flow chart illustrating anexemplary method for adjusting a charged particle beam apparatus with athermal conditioning station, consistent with embodiments of the presentdisclosure. The method may be performed by a charged particle beaminspection system 400 (such as charged particle beam inspection system400 of FIG. 4).

In step 910, the inspection system loads a wafer to a wafer stage in amain chamber (such as wafer stage 495 in main chamber 490 of FIG. 4) forinspection. The wafer may have been thermally preconditioned in thethermal conditioning station (such as thermal conditioning station 410of FIG. 4). In some embodiments, after the wafer (such as wafer 480 ofthe FIG. 4) is transported to the wafer stage, another wafer (such aswafer 420 of the FIG. 4) may be loaded to the thermal conditioningstation while the inspection of the first wafer in is progress in themain chamber. This thermal conditioning before transporting a wafer tothe wafer stage for inspection may improve the overall throughput of theinspection system by minimizing a wafer deformation caused by a wafertemperature drift as explained in further details with respect to FIG.3.

In step 920, the inspection system scans the wafer to measure some wafercharacteristics, which can be provided to a controller (such ascontroller 450 of FIG. 4) for adjusting the thermal conditioningstation. For example, the inspection system may scan the wafer andproduce one or more images of the wafer (such as wafer images 710 and760 of FIG. 7 or wafer images 810, 820, and 830 of FIG. 8). These waferimages may show a plurality of structures or patterns on the wafer,wherein the structures or the patterns are embedded on the wafer duringa semiconductor manufacturing process. The inspection system may analyzethe wafer images and measure the characteristics of the structures. Forexample, locations of the structures or distances between the structuresmay be identified through the analysis.

In step 930, the inspection system analyzes the identifiedcharacteristics of the structures to determine a temperaturecharacteristic of the wafer. In some embodiments, as explained in detailwith respect to FIG. 7, the controller of the inspection system maycompare the measured locations of the structures to correspondinglocations of the structures in a reference data to determine atemperature characteristic of the wafer. In some embodiments, asexplained in detail with respect to FIG. 8, the inspection system mayproduce multiple wafer images at different times over a time sequenceand compare the characteristics of the structures in those multipleimages to determine the temperature characteristic of the wafer.

In step 940, the controller of the inspection system determines thetemperature characteristic of the wafer based on the measuredcharacteristics of the structures, including the locations of thestructures and the distances between the structures. In someembodiments, the temperature characteristic of the wafer may comprise anactual temperature of the wafer. In other embodiments, the temperaturecharacteristic of the wafer may comprise an initial temperaturedifference between the wafer and the wafer stage (e.g., the temperaturedifference when the wafer is initially loaded onto the wafer stage forinspection).

In step 950, the controller adjusts the thermal conditioning stationsbased on the determined temperature characteristic of the wafer. Forexample, the controller may adjust the temperature setpoint of thethermal conditioning station to improve the efficiency of thermalconditioning on the wafers in pipeline (e.g., wafer 420 of FIG. 4 andother wafers in FOUPs).

The embodiments may further be described using the following clauses:

1. A method for determining a temperature characteristic of a waferusing a charged particle beam apparatus, the wafer including a pluralityof structures, comprising:

scanning the wafer with the charged particle beam apparatus to measureone or more characteristics of the plurality of structures on the wafer;

analyzing the one or more characteristics of the plurality ofstructures; and

determining the temperature characteristic based on the analysis of theone or more characteristics of the plurality of structures.

2. The method of clause 1, wherein the temperature characteristic of thewafer comprises a temperature of the wafer.3. The method of any one of clauses 1 and 2, further comprising:

-   -   comparing the one or more characteristics to corresponding one        or more characteristics in a reference data.        4. The method of clause 3, wherein the one or more        characteristics of the plurality of structures comprise        locations of the plurality of structures.        5. The method of clause 3, wherein the one or more        characteristics of the plurality of structures comprise a        distance between the plurality of structures.        6. The method of any one of clauses 3 to 5, wherein the        reference data comprises a GDS layout data.        7. The method of any one of clauses 3 to 5, wherein the        reference data comprises a scan data by a charged particle beam        apparatus.        8. The method of any one of clauses 3 to 7, wherein the        reference data is associated with a known temperature of the        wafer.        9. The method of any one of clauses 3 to 8, wherein the        reference data comprises a determined temperature characteristic        of a previously analyzed wafer.        10. The method of any one of clauses 1 and 2, further        comprising:

measuring a first set of the one or more characteristics of theplurality of structures at a first time over a time sequence;

measuring a second set of the one or more characteristics of theplurality of structures at a second time over the time sequence; and

comparing the first set and the second set of the one or morecharacteristics of the plurality of structures.

11. The method of clause 10, wherein the one or more characteristics ofthe plurality of structures comprise locations of the plurality ofstructures.12. The method of clause 10, wherein the one or more characteristics ofthe plurality of structures comprise a distance between the plurality ofstructures.13. The method of any one of clauses 1 to 12, further comprising:

providing the temperature characteristic to a controller of the chargedparticle beam apparatus; and

adjusting a thermal conditioning station to thermally precondition anext wafer to be inspected.

14. A non-transitory computer readable medium including a set ofinstructions that is executable by one or more processors of acontroller to cause the controller to perform a method for determining atemperature characteristic of a wafer using a charged particle beamapparatus, the wafer including a plurality of structures, the methodcomprising:

scanning the wafer with the charged particle beam apparatus to measureone or more characteristics of the plurality of structures on the wafer;

analyzing the one or more characteristics of the plurality ofstructures; and

determining the temperature characteristic based on the analysis of theone or more characteristics of the plurality of structures.

15. The computer readable medium of clause 14, wherein the temperaturecharacteristic of the wafer comprises a temperature of the wafer.16. The computer readable medium of any one of clauses 14 and 15,wherein the set of instructions that is executable by the one or moreprocessors of the controller to cause the controller to further perform:

comparing the one or more characteristics to corresponding one or morecharacteristics in a reference data.

17. The computer readable medium of clause 16, wherein the one or morecharacteristics of the plurality of structures comprise locations of theplurality of structures.18. The computer readable medium of clause 16, wherein the one or morecharacteristics of the plurality of structures comprise a distancebetween the plurality of structures.19. The computer readable medium of any one of clauses 16 to 18, whereinthe reference data comprises a GDS layout data.20. The computer readable medium of any one of clauses 16 to 18, whereinthe reference data comprises a scan data by a charged particle beamapparatus.21. The computer readable medium of any one of clauses 16 to 20, whereinthe reference data is associated with a known temperature of the wafer.22. The computer readable medium of any one of clauses 16 to 21, whereinthe reference data comprises a determined temperature characteristic ofa previously analyzed wafer.23. The computer readable medium of any one of clauses 14 and 15,wherein the set of instructions that is executable by the one or moreprocessors of the controller to cause the controller to further perform:

measuring a first set of the one or more characteristics of theplurality of structures at a first time over a time sequence;

measuring a second set of the one or more characteristics of theplurality of structures at a second time over the time sequence; and

comparing the first set and the second set of the one or morecharacteristics of the plurality of structures.

24. The computer readable medium of clause 23, wherein the one or morecharacteristics of the plurality of structures comprise locations of theplurality of structures.25. The computer readable medium of clause 23, wherein the one or morecharacteristics of the plurality of structures comprise a distancebetween the plurality of structures.26. The computer readable medium of any one of clauses 14 to 25, whereinthe set of instructions that is executable by the one or more processorsof the controller to cause the controller to further perform:

providing the temperature characteristic to a controller of the chargedparticle beam apparatus; and

adjusting a thermal conditioning station to thermally precondition anext wafer to be inspected.

27. A method for adjusting a charged particle beam apparatus with athermal conditioning station, comprising:

scanning a wafer on a wafer stage with the charged particle beamapparatus to measure one or more characteristics of a plurality ofstructures on the wafer;

analyzing the one or more characteristics of the plurality ofstructures;

determining a temperature characteristic of the wafer based on theanalysis of the one or more characteristics of the plurality ofstructures; and

adjusting the thermal conditioning station based on the temperaturecharacteristic.

28. The method of clause 27, wherein analyzing the one or morecharacteristics of the plurality of structures comprises:

obtaining one or more images of the wafer,

measuring the one or more characteristics of the plurality of structuresof the wafer based on the one or more images, and

comparing the one or more characteristics of the plurality of structuresto corresponding one or more characteristics of the plurality ofstructures in a reference data.

29. The method of clause 28, wherein the one or more characteristics ofthe plurality of structures comprise locations of the plurality ofstructures.30. The method of clause 28, wherein the one or more characteristics ofthe plurality of structures comprise a distance between the plurality ofstructures.31. The method of any one of the clauses 28 to 30, wherein the referencedata are associated with a known temperature of the wafer.32. The method of any one of clauses 28 to 31, wherein the referencedata comprises a determined temperature characteristic of a previouslyanalyzed wafer.33. The method of clause 27, wherein analyzing the one or morecharacteristics of the plurality of structures comprises:

obtaining a first image of the wafer at a first time over a timesequence,

obtaining a second image of the wafer at a second time over the timesequence,

measuring a first set of the one or more characteristics based on thefirst image,

measuring a second set of the one or more characteristics based on thesecond image, and

comparing the first set and the second set of the one or morecharacteristics of the plurality of structure.

34. The method of clause 33, wherein the one or more characteristics ofthe plurality of structures comprise locations of the plurality ofstructures.35. The method of clause 33, wherein the one or more characteristics ofthe plurality of structures comprise a distance between the plurality ofstructures.36. The method of any one of clauses 33 to 35, further comprising:

obtaining a third image of the wafer at a third time over the timesequence;

measuring a third set of the one or more characteristics based on thethird image; and

conducting an extrapolation process based on the first set, the secondset, and the third set of the one or more characteristics of theplurality of structure.

37. The method of clause 36, wherein the extrapolation comprises anexponential extrapolation.38. The method of any one of clauses 27 to 37, wherein the thermalconditioning station comprises a load lock unit.39. The method of any one of clauses 27 to 38, further comprising:

identifying an alignment characteristic of the wafer at a local level;and

determining whether the thermal conditioning station needs to beadjusted.

40. A charged particle beam apparatus, comprising:

a thermal conditioning station configured to precondition a wafertemperature;

a particle beam imaging tool to generate one or more images of a waferon a wafer stage; and

a controller having circuitry to cause the charged particle beamapparatus to perform:

-   -   scanning the wafer with the particle beam imaging tool to        measure one or more characteristics of a plurality of structures        on the wafer;    -   analyzing the one or more characteristics of the plurality of        structures;    -   determining a temperature characteristic of the wafer based on        the analysis of the one or more characteristics of the plurality        of structures; and    -   adjusting the thermal conditioning station based on the        temperature characteristic.        41. The apparatus of clause 40, wherein the controller        performing analyzing the one or more characteristics of the        plurality of structures comprises:

obtaining the one or more images of the wafer,

measuring the one or more characteristics of the plurality of structuresof the wafer based on the one or more images, and

comparing the one or more characteristics of the plurality of structuresto corresponding one or more characteristics of the plurality ofstructures in a reference data.

42. The apparatus of clause 41, wherein the one or more characteristicsof the plurality of structures comprise locations of the plurality ofstructures.43. The apparatus of clause 41, wherein the one or more characteristicsof the plurality of structures comprise a distance between the pluralityof structures.44. The apparatus of any one of the clauses 41 to 43, wherein thereference data are associated with a known temperature of the wafer.45. The apparatus of any one of the clauses 41 to 44, wherein thereference data comprises a determined temperature characteristic of apreviously analyzed wafer.46. The apparatus of clause 40, wherein the controller performinganalyzing the one or more characteristics of the plurality of structurescomprises:

obtaining a first image of the wafer at a first time over a timesequence,

obtaining a second image of the wafer at a second time over the timesequence,

measuring a first set of the one or more characteristics based on thefirst image,

measuring a second set of the one or more characteristics based on thesecond image, and

comparing the first set and the second set of the one or morecharacteristics of the plurality of structure.

47. The apparatus of clause 46, wherein the one or more characteristicsof the plurality of structures comprise locations of the plurality ofstructures.48. The apparatus of clause 46, wherein the one or more characteristicsof the plurality of structures comprise a distance between the pluralityof structures.49. The apparatus of any one of clauses 46 to 48, wherein the controllerperforming analyzing the one or more characteristics of the plurality ofstructures further comprises:

obtaining a third image of the wafer at a third time over the timesequence;

measuring a third set of the one or more characteristics based on thethird image; and

conducting an extrapolation process based on the first set, the secondset, and the third set of the one or more characteristics of theplurality of structure.

50. The apparatus of clause 49, wherein the extrapolation comprises anexponential extrapolation.51. The apparatus of any one of clauses 40 to 50, wherein the thermalconditioning station comprises a load lock unit.52. The apparatus of any one of clauses 40 to 51, wherein the controllerfurther performs:

identifying an alignment characteristic of the wafer at a local level,and determining whether the thermal conditioning station needs to beadjusted.

It is appreciated that a controller of the wafer conditioning systemcould use software to control the functionality described above. Forexample, the controller may produce multiple images of wafers. Thecontroller may analyze the images of wafers and determine a temperaturecharacteristic of the wafer. The controller may send instructions to aheater/cooler (such as heater/cooler 460 of FIG. 4) to adjust thetemperature of heat transfer elements. The software may be stored on anon-transitory computer readable medium. Common forms of non-transitorymedia include, for example, a floppy disk, a flexible disk, hard disk,solid state drive, magnetic tape, or any other magnetic data storagemedium, a CD-ROM, any other optical data storage medium, any physicalmedium with patterns of holes, a RAM, a PROM, and EPROM, cloud storage,a FLASH-EPROM or any other flash memory, NVRAM, a cache, a register, anyother memory chip or cartridge, and networked versions of the same.

Although the disclosed embodiments have been explained in relation toits preferred embodiments, it is to be understood that othermodifications and variation can be made without departing the spirit andscope of the subject matter as hereafter claimed.

1. A charged particle beam apparatus, comprising: a thermal conditioningstation configured to precondition a wafer temperature; a particle beamimaging tool to generate one or more images of a wafer on a wafer stage;and a controller having circuitry to cause the charged particle beamapparatus to perform: scanning the wafer with the particle beam imagingtool to measure one or more characteristics of a plurality of structureson the wafer; analyzing the one or more characteristics of the pluralityof structures; determining a temperature characteristic of the waferbased on the analysis of the one or more characteristics of theplurality of structures; and adjusting the thermal conditioning stationbased on the temperature characteristic.
 2. The apparatus of claim 1,wherein the controller performing analyzing the one or morecharacteristics of the plurality of structures comprises: obtaining theone or more images of the wafer, measuring the one or morecharacteristics of the plurality of structures of the wafer based on theone or more images, and comparing the one or more characteristics of theplurality of structures to corresponding one or more characteristics ofthe plurality of structures in a reference data.
 3. The apparatus ofclaim 2, wherein the one or more characteristics of the plurality ofstructures comprise locations of the plurality of structures.
 4. Theapparatus of claim 2, wherein the one or more characteristics of theplurality of structures comprise a distance between the plurality ofstructures.
 5. The apparatus of claim 2, wherein the reference data areassociated with a known temperature of the wafer.
 6. The apparatus ofclaim 2, wherein the reference data comprises a determined temperaturecharacteristic of a previously analyzed wafer.
 7. The apparatus of claim1, wherein the controller performing analyzing the one or morecharacteristics of the plurality of structures comprises: obtaining afirst image of the wafer at a first time over a time sequence, obtaininga second image of the wafer at a second time over the time sequence,measuring a first set of the one or more characteristics based on thefirst image, measuring a second set of the one or more characteristicsbased on the second image, and comparing the first set and the secondset of the one or more characteristics of the plurality of structure. 8.The apparatus of claim 7, wherein the one or more characteristics of theplurality of structures comprise locations of the plurality ofstructures.
 9. The apparatus of claim 7, wherein the one or morecharacteristics of the plurality of structures comprise a distancebetween the plurality of structures.
 10. The apparatus of claim 7,wherein the controller performing analyzing the one or morecharacteristics of the plurality of structures further comprises:obtaining a third image of the wafer at a third time over the timesequence; measuring a third set of the one or more characteristics basedon the third image; and conducting an extrapolation process based on thefirst set, the second set, and the third set of the one or morecharacteristics of the plurality of structure.
 11. The apparatus ofclaim 10, wherein the extrapolation comprises an exponentialextrapolation.
 12. The apparatus of claim 1, wherein the thermalconditioning station comprises a load lock unit.
 13. The apparatus ofclaim 1, wherein the controller further performs: identifying analignment characteristic of the wafer at a local level, and determiningwhether the thermal conditioning station needs to be adjusted.
 14. Anon-transitory computer readable medium including a set of instructionsthat is executable by one or more processors of a controller to causethe controller to perform a method for determining a temperaturecharacteristic of a wafer using a charged particle beam apparatus, thewafer including a plurality of structures, the method comprising:scanning the wafer with the charged particle beam apparatus to measureone or more characteristics of the plurality of structures on the wafer;analyzing the one or more characteristics of the plurality ofstructures; and determining the temperature characteristic based on theanalysis of the one or more characteristics of the plurality ofstructures.
 15. A method for determining a temperature characteristic ofa wafer using a charged particle beam apparatus, the wafer including aplurality of structures, comprising: scanning the wafer with the chargedparticle beam apparatus to measure one or more characteristics of theplurality of structures on the wafer; analyzing the one or morecharacteristics of the plurality of structures; and determining thetemperature characteristic based on the analysis of the one or morecharacteristics of the plurality of structures.